Curable transparent rubber composition, a cured transparent rubber composition made thereof, and manufacturing process for the same

ABSTRACT

The present disclosure provides a solid curable transparent rubber composition containing one or more synthetic isoprene polymer, one or more transparent polymer, one or more curing agent, additives that do not influence transparency and one or more polyalkenamers. The solid curable transparent rubber composition, once cured, has a haze of less than 30% and a total light transmission of more than 80%. The disclosure further provides a cured transparent rubber composition made thereof, and a manufacturing process for the cured composition. The present disclosure also provides an article including the rubber composition, in particular shoes with transparent soles.

TECHNICAL FIELD

The present disclosure relates to a curable transparent rubbercomposition, a cured transparent rubber composition made thereof, and amanufacturing process for the cured composition. The present disclosurealso relates to an article including the rubber composition, inparticular shoes with transparent soles.

BACKGROUND OF THE INVENTION

A cured transparent rubber composition is a material which is toughwhile exhibiting rubber behavior and through which visible light passes,which for many applications is a desirable property. Applicationswherein cured transparent rubber compositions may be used include, butnot limited to, footwear products, tires, clothes, mask, rain gear,toys, damping materials, building components, coating material forwiring, packaging materials, protection members for computers, computerperipherals, contraceptive devices, sex toys, artificial nipples,disposable diapers, stationery, containers, food trays, balls forsports, ball chairs, protection films, seals, and key covers, shoesoles, medical stoppers and the like. Shoe soles and similarapplications are of interest, provided the minimum requirements withrespect to abrasion resistance are met.

Thus, a transparent shoe sole should be clear and transparent (i.e.,total transmittance greater than 80%, with haze below 30%, bothaccording to ASTM D1003-13), but also have strong mechanical properties,good UV stability, excellent shelf life as unvulcanized compound andhave preferably an abrasion resistance (ISO 4649, method A) of less than200 mm3.

In WO2008091847 a composition is described comprising at least onepolyisoprene and at least one EAODM polymer. Said polymer has a goodabrasion resistance and good tear resistance. Said rubber compositioncomprises 28.9 wt. % of natural rubber, 9.5 wt. % of polybutadiene, 12.4wt. % of the EAODM, 24.8 wt. % of carbon black and 1.38 wt. % of avulcanization system. Unfortunately, said system is not transparent. Forthe avoidance of doubt, the EAODM (NDR 46140) is not a polyalkenamer.

In JP2011110105 a shoe sole forming sheet is described that is usefulfor efficiently joining a crosslinked rubber layer as a stud and athermoplastic elastomer layer as a sole. Paragraph 160 of the translatedspecification describes a Rubber composition 1 which comprises “50 partsby weight of crude rubber, and butadiene rubber (the Dow Chemical Co.make --) “Buna EM1500” 50 part by weight and polyoctenylene (the productmade from EBONIKKU GmbH --) “BESUTENEMA 8012” 5 part by weight and clay(the product made from Hoffmann Mineral --) “Silitin Z86” 25 parts byweight, 45 parts by weight of carbon black (N335), 10 parts by weight ofplasticizers (the product made from Bayer, “Vulcanol 88”), 1 part byweight of stearic acid, and a vulcanization active agent (the productmade from Elaborate Chemicals, and “Hicross M”--)”. Said system, basedon natural rubber and high amounts of additives, is not transparent.

(EP1932688) concerns a pneumatic run-flat tire. The elastomeric layerscomprise a rubber composition comprising 100 parts by weight of naturalrubber or synthetic rubber, 10-30 phr of silica and from 1 to 20 phr ofpolyoctenamer. Again, said composition is not transparent.

Excellent transparent rubber compositions have for instance beendescribed in WO2014132718. Even though in this application an improvedbalance has been found between rubber properties such as hardness andstrength on the one hand and transparency on the other hand, there isstill a need for further improvement, in particular with respect toabrasion resistance. This requirement is particularly important forsport shoes, where lower abrasion resistance is required as compared toordinary shoes (e.g., <120 mm3). Now a new composition has been foundthat can be used for shoe soles and other applications.

SUMMARY OF THE INVENTION

Accordingly a solid curable transparent rubber composition is providedthat once cured has a haze of less than 30% and a total lighttransmission of more than 80%, both measured according to ASTM D1003-13,comprising:

-   -   Component (a): from 35-60 wt. % of one or more synthetic        isoprene polymers having a refractive index of between 1.500 to        1.525 at 23° C.;    -   Component (b): from 35-60 wt. % of one or more transparent        polymers different from isoprene polymers wherein the difference        between the refractive indices of component (a) and (b) is 0.100        or less;    -   Components (c) and (d): from 0.05-8.0 wt. % of a curing agent,        optionally with a co-agent, and    -   Component (e): from 0.01-20 wt. % of additives that do not        influence the transparency,

characterized in that the composition further comprises:

-   -   Component (f): from 1-4 wt. % of one or more polyalkenamers,        wherein all amounts are in percentages by weight on the total        composition.

The present disclosure also provides a transparent, cured rubbercomposition, based on the curable composition mentioned above. Thepresent disclosure also provides a process for manufacturing atransparent, cured rubber composition, wherein the process comprisingthe acts of:

-   -   mixing components (a), (b) and (e) to obtain a mixture thereof;    -   adding a curing agent (c) and co-agent (d) to the mixture; and    -   uniformly kneading the mixture.

DESCRIPTION OF THE INVENTION

The term of “haze” means the degree of dimness in a transparentmaterial, measured according to ASTM D1003-13, by using 2 mm-thick sheetof a test material. The value of haze is determined as a percent oftransmitted light which strays from the incident light in the angle of0.044 rad or more by forward scattering.

The term of “TT” which stands for “total luminous transmittance” meansthe ratio of light beam passed through a transparent material, measuredaccording to ASTM D1003-13. The value of total luminous transmittance isdetermined as the ratio of total transmitting light flux with respect toparallel incident light flux on a test article.

The term of “Type A Durometer Hardness” or “Hs” means the hardness of arubber composition measured according to ASTM D2240. The value of Hs isdetermined, in the present specification, from the following procedure:constantly pushing a plunger onto a test article, and measuring thedepth of the pushed plunger in the article at 0 sec or 30 sec after thepushing.

The term of “tear strength” means the tear strength of a rubbercomposition measured according to ASTM D624. The value of tear strengthis determined, in the present specification, by using 2 mm-thick sheetof a test material, and converted in N/mm unit.

The term of “vinyl content” refers to the amount of a conjugated dienewhich is polymerized via 1,2-addition (in the case of butadiene—it wouldbe 3,4-addition in the case of isoprene). Although a pure “vinyl” groupis formed only in the case of 1,2-addition polymerization of1,3-butadiene, the effects of 3,4-addition polymerization of isoprene(and similar addition for other conjugated dienes) on the finalproperties of the block copolymer will be similar. The result of theaddition above, a pendant vinyl group on the polymer skeleton will beproduced. The vinyl content in a polymer may be measured using aconventional technique in the art such as proton NMR.

The vinyl content is effectively controlled by varying the relativeamount of the distribution agent. As will be appreciated, thedistribution agent serves two purposes—it creates the controlleddistribution of the mono alkenyl arene and conjugated diene, and alsocontrols the microstructure of the conjugated diene. Suitable ratios ofdistribution agent to lithium are disclosed in U.S. Pat. No. RE 27,145,which disclosure is incorporated by reference.

The terms of “plasticizer oil”, “plasticizer”, and “softener” mean a(oil-based) compound known as an additive for changing properties of amaterial in the art. The plasticizer may include, but not limited to,paraffin oil, mineral oil, ester oil, hydrocarbon-based syntheticlubricating oils, naphthenic oils, and vegetable oils.

As used herein, unless otherwise noted, the term “molecular weight(s)”refers to the true molecular weight in g/mole of the polymer or block ofthe copolymer. The molecular weights referred to in this specificationand claims can be measured with gel permeation chromatography (GPC)using polystyrene calibration standards, such as is done according toASTM 3536. GPC is a well-known method wherein polymers are separatedaccording to molecular size, the largest molecule eluting first. Thechromatograph is calibrated using commercially available polystyrenemolecular weight standards. The molecular weight of polymers measuredusing GPC so calibrated are styrene equivalent molecular weights, alsoknown as apparent molecular weights. The styrene equivalent molecularweight may be converted to true molecular weight when the styrenecontent of the polymer and the vinyl content of the diene segments areknown. The detector used is preferably a combination ultraviolet andrefractive index detector. The molecular weights expressed herein aremeasured at the peak of the GPC trace, converted to true molecularweights, and are commonly referred to as “peak molecular weights”. Whenexpressed as apparent molecular weights they are similarly determinedwith the exception that consideration of the block copolymer compositionand the subsequent conversion to true molecular weights is not done.

The words of “comprising”, “including”, and “containing” mean in thepresent specification, unless otherwise noted, that an article orcomponent connotes or has an element(s). The spirit of the words mayembrace both an internal and external additions.

In the case that the word of “about”, “around”, or “appropriately” isprefixed to a value, in the present specification, the value can includea tolerance of at least plus/minus 10 percent.

Component (a)

Synthetic isoprene polymers are known. This definition includeshomopolymers and copolymers of isoprene, wherein at least 50 mole % ofthe polymer backbone is based on isoprene. Homopolymers are oftenreferred to as Isoprene Rubber, or IR. The isoprene polymer can be ananionically produced IR, IR produced by Ziegler-Natta catalysis, or witha neodymium catalyst. Natural rubber (NR) is likewise a homopolymer ofisoprene. However, NR is not suitable. NR is not a synthetic isoprenepolymer. Generally it lacks sufficient transparency and typically is tooyellow or even brown. Copolymers include polymers comprising isopreneand another conjugated diene and/or olefinically unsaturated monomer inthe polymer backbone. Examples include copolymers of butadiene andisoprene, or isoprene and styrene, and the like. Copolymers may berandom, tapered, block or otherwise structured. Isoprene polymers may belinear or branched. Moreover, they may be functionalized.

To achieve better tear strength, the isoprene polymers preferably have amolecular weight greater than 250,000, more preferably greater than500,000. Moreover, in term of isoprene homopolymers, they preferablyhave a cis content of greater than 80%. The high cis content is believedto be beneficial to the flexibility of the composition. Then again, thecis content is not the only factor influencing the flexibility, andisoprene homopolymers with a flexibility below 80% may still be useful.

It is important that the one or mixture of isoprene polymers used ascomponent (a) has a refractive index of between 1.500 to 1.525 at 23° C.Best results have been achieved with anionically produced IR, such asCariflex® IR0307 and Cariflex IR0310 (manufactured by Kraton Polymers).Anionically produced IR is therefore preferred. In terms oftransparency/haze and yellowness index, next best results were achievedwith IR produced with a neodymium catalyst, followed by IR produced byZiegler-Natta catalysis.

Component (a) is preferably present in an amount of 40-55 wt. %, morepreferably in an amount of 45-50 wt. %

Component (b)

The polymer(s) used as component (b) has/have a refractive index that isvery similar to that of component (a). Accordingly, the differencebetween the refractive indices of component (a) and (b) is 0.100 orless, preferably 0.050 or less, more preferably 0.020 or less.

Since component (b) is processed together with component (a), its mixingprocessing temperature should be relatively low. Polymers having amixing processing temperature above 150° C. generally are not suitableas this would require elevated temperatures that may during prolongedmixing procedures adversely affect component (a) (discoloration anddegradation). Preferably, the mixing processing temperature of component(b) is at most 135° C., more preferably at most 130° C.

Component (b) is preferably a butadiene polymer, more preferablypolybutadiene. Provided it is transparent and the requirements inrespect of the refractive index and mixing processing temperature aremet, other polymers may be used instead or in combination with abutadiene polymer. Such polymers include polymers made from C₄ to C₂₀olefins; thermoplastic elastomers (TPEs), styrene-butadiene rubber(SBR), ethylene-propylene rubber (EPM), ethyl ene-propyl ene-di enerubber (EPDM), urethane rubber, and any other polymer which is referredto as rubber in the prior art.

Particularly suitable is syndiotactic 1,2-polybutadiene provided by JSR,e.g., grades RB810, RB820, RB830 or RB840.

Component (b) is preferably present in an amount of 40-55 wt. %, morepreferably in an amount of 45-50 wt. %.

Components (c) and (d)

The curing agent (c) is preferably a peroxide in view of lowcontamination and therefore higher transparency in a final product.Excellent results have been achieved with peroxides selected from thegroup consisting of 2,5-dimethyl-2,5-di-(t-butyl peroxy)hexane, dicumylperoxide, benzoyl peroxide,1,1-bis-(t-butylperoxy)-3,5,5-trimethylcyclohexane, diisobutyrylperoxide, cumylperoxy neodecanoate, di-n-propylperoxy dicarbonate,di-isopropyl peroxy dicarbonate, di-sec-butylperoxy dicarbonate,1,1,3,3-tetramethyl-butylperoxy neodecanoate, di-(4-t-butylcyclohexyl)peroxy dicarbonate, di(2-ethylhexyl)peroxy dicarbonate,t-hexylperoxy neodecanoate, t-butylperoxy neodecanoate, t-butylperoxyneoheptanoate, t-hexylperoxy pivalate, t-butylperoxy pivalate,di(3,5,5-trimethyl-hexanoyl) peroxide, dilauroyl peroxide,1,1,3,3-tetramethyl-butylperoxy-2-ethylhexanoate, disuccinic acidperoxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane,t-hexylperoxy-2-ethylhexanoate, di(4-methyl-benzoyl) peroxide,t-butylperoxy-2-ethylhexanoate, di(3-methyl-benzoyl) peroxide,benzoyl(3-methyl-benzoyl) peroxide, dibenzoyl peroxide,1,1-di(t-butylperoxy)-2-methyl-cyclohexane,1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane,1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)cyclohexane,2,2-di(4,4-di(t-butylperoxy)cyclohexyl)propane, t-hexylperoxyisopropylmonocarbonate, t-butylperoxy maleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy laurate, t-butylperoxyisopropyl monocarbonate,t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxy benzoate,2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxy acetate,2,2-di-(t-butylperoxy)butane, t-butylperoxy benzoate,n-butyl-4,4-di-(t-butylperoxy) valerate,di(2-t-butylperoxyisopropyl)benzene, di-t-hexyl peroxide, t-butylcumylperoxide, di-t-butyl peroxide, p-menthane hydroperoxide,2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, diisopropylbenzenehydroperoxide, 1,1,3,3-tetramethyl-butyl hydroperoxide, cumenehydroperoxide, and t-butyl hydroperoxide.

More preferably, the peroxide is2,5-dimethyl-2,5-di(t-butylperoxy)hexane (e.g., Trigonox® 101 from AKZOor Perhexa® 25B by NOF Corporation) or1,1-di(tert-butylperoxy)cyclohexane (eg. Perhexa® C by NOF Corporation,Luperox® 331M80 from Arkema, or Trigonox 22 from AKZO), in order tosuppress malodour and residue amount. Also suitable given its stabilityand ease of use is 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3 (e.g.,Trigonox 145 from AKZO).

The amount of curing agent (c) may also be expressed in terms of partsby hundred parts of curable components, here components (a), (b) and(f). Preferably, the amount of curing agent (c) varies from 0.05 to 1.5phr, more preferably from 0.1 to 1.0 phr.

As co-agent (d) any one or more selected from the group consisting ofethylene glycol methacrylate (EGDMA), trimethylolpropane trimethacrylate(TMPTMA), triallyl isocyanurate, triallyl cyanurate, diethylene glycoldiacrylate, and neophenylene glycol diacrylate may be used.

Co-agent (d) is optional. The lower limit is therefore zero. Then again,its amount will not be more than 7.95 wt. %, when used with 0.05 wt. %of curing agent. With minute amounts of curing agent, e.g., in the rangeof 0.05-0.1 wt. % of curing agent, the relative amount of co-agent maybe high. For instance, the weight ratio (c) to (d) in the above examplewith 7.95 wt. % co-agent used with 0.05 wt. % of curing agent is 1:159.The weight ratio may therefore vary from 100:1 to 1:100. With smallamounts of curing agent, e.g., 0.01-0.09 wt. % of curing agent, theweight ratio may vary up to 1:88. With minor amounts of curing agent,e.g., 0.1-0.15 wt. % of curing agent, the weight ratio may vary up to1:53. In higher amounts of curing agent, the curing agent and theco-agent are preferably used in a weight ratio (c) to (d) of 1:2-10,more preferably 1:3-7. Particularly preferred combinations are(2,5-dimethyl-2,5-di(t-butylperoxy)hexane,1,1-di(tert-butylperoxy)cyclohexane or2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3 as component (c) with EGDMAor TMPTA as component (d).

Additives (e)

The composition of the present embodiments may further includeadditional components as long as the component(s) do not (in the amountused) affect the haze and transparency. The additional component mayinclude, but is not limited to, colorants, modifiers, finishing agents(e.g., zinc laurate), antioxidants (e.g., monophenol, bisphenol,polyphenol, sulfur, phosphorus-based compounds such as Irganox® 1010,Irgafos® 168, Irganox® 1726 and Irganox PS800 manufactured by BASF),reducing agents, oxygen scavengers, light stabilizers, antacids, pHstabilizers, surface treatment agents, heat stabilizers, colorants,fillers, surfactants, gelling agents, biocides, UV absorbents (e.g.,salicylic acid, benzophenone, benzotriazole, cyanoacrylate, and hinderedamine), dusting agents (e.g., polyolefin such as polyethylene, silica,talc, calcium carbonate powder), flame retardants, and polyphosphoricacid. In particular large amount of fillers, dusting agents, and similarnon-transparent additives should be avoided, and is preferably kept toat most 5 wt. %, preferably at most 2 wt. %. A common additive that ispreferably avoided, with a preferred maximum of 1 wt. %, is carbonblack. Higher amounts will quickly and adversely affect the haze andtransparency of the composition. Similar upper limits exist forinorganic fillers and the like.

Preferably, the present composition is substantially free of oil as asoftener to avoid oil bleeding.

The colorant may be used such that the composition has transparent ortranslucent coloring such as clear blue, clear red, and clear green. Thecolorant may include any conventional colorants used in the art, such ascolor pigments, extender pigments, anti-corrosive pigments, andfunctional pigments (e.g., phthalocyanine green, titanium, iron blue,iron oxide, lead suboxide, and zinc sulfide).

Component (f)

Polyalkenamers are known. This is a class of unsaturated polymer formedby so-called ring-opening methathesis-polymerization (ROMP) ofcyclopentene, cyclooctene, cyclopentadiene and/or norbonene, etc. Themost common representative of this class is trans-polyoctenamer,generally abbreviated to TOR and commercially available as Vestenamer®from Evonik Degussa GmbH. The properties of TOR are for instancedescribed in “A New Rubber: trans-Polyoctenamer”, by Adolf Draxler inElastomerics, February 1983, pp. 16-20. Vestenamer is available in 2grades, 8012 with a trans content of about 80%, and 6213 with a transcontent of about 60%. The former is preferred. The product is a mixtureof two inseparable components:

Although this reference describes TOR blends, nothing was disclosed withrespect to blends of a polyalkenamer, and TOR in particular, in acurable transparent rubber composition, further comprising one or moreisoprene polymers having a refractive index of between 1.500 to 1.525 at23° C. As illustrated in the examples, the novel composition providesexcellent transparency, mechanical properties, in combination with asignificantly increased abrasion resistance.

Component (f) is preferably present in an amount of 1.5-4.5 wt. %, morepreferably in an amount of 2-4 wt. %.

The transparent composition of the present embodiments may preferablyhave less than 30% of haze, more preferably 20% or less of haze, morefurther preferably 15% or less of haze in view of enough transparency.If the haze is 35% or more, the transparency of the composition will betoo low to meet the practical and aesthetic needs of the market.

The composition of the present embodiments may preferably have 35 ormore of Type A Durometer hardness measured at 30 seconds, morepreferably from 35 to 70, more further preferably from 40 to 70, stillmore further preferably from 50 to 70. In the case that the presentcomposition is incorporated to a product to be used under a severeenvironment, such as footwear (e.g., shoe sole) and rubber tire, theType A Durometer hardness may preferably be around 60 to 70.

Preferably, the present composition has 80% or more, preferably 84% ormore of total luminous transmittance measured according to ASTMD1003-13. If the total luminous transmittance is less than 80%, thecomposition will lack enough transparency.

Preferably, the composition has 10 N/mm or more, preferably 10 N/mm to50 N/mm, more preferably 10 N/mm to 40 N/mm of tear strength measured by2 mm-thick sheet (and converted in N/mm unit) according to ASTM D624. Ifthe tear strength is less than 10 N/mm, the composition may lackdurability.

Preferably, the composition has 200 mm3 or less, preferably 160 mm³ orless, more preferably 140 mm³ or less of abrasion resistance accordingto ISO 4649, method A. If the abrasion resistance is more than 200 mm³,a shoe sole made therefrom cannot be used for sport shoes.

Manufacturing Procedure

The present disclosure also provides a process for manufacturing atransparent, cured rubber composition, wherein the process comprisingthe acts of:

-   -   mixing components (a), (b) and (f) to obtain a mixture thereof;    -   adding a curing agent (c) and co-agent (d) to the mixture; and        uniformly kneading the mixture and curing the same.

The conditions for mixing and for curing are well-known to a personskilled in the art and depends on the equipment used. Mixing may forinstance be performed according to a “roller mill procedure”. This willstart with the mastication of the synthetic polyisoprene using a rollermill that is operating at conventional conditions. Roller speed willgenerally be in the range of 17 to 20 rotations per minute, whereas therollers are maintained at about 55° C. In step 1, component (b) (e) and(f) are combined with the masticated synthetic polyisoprene. One maystart with component (b) and introduce this onto the roller mill. Theroller mill may be operated at about 120° C. Next component (a), themasticated synthetic rubber, component (e) and/or component (f) may beadded. The order is not important, as long as the produced is well mixedand the product remains transparent and basically colourless. Due tofriction the temperature may rise. Preferably the mixing of thecomponents is done at 130° C. or less. Higher temperatures may be used,e.g., where the temperature is allowed to rise to 150° C. despite thenegative effects on the colour and stability of component (a), providedthe time that component (a) is subjected to the elevated temperature iskept short. Once the mixing is completed, the mixture is removed fromthe roller mill (“sheet off”).

In step (2), the roller mill is operated at about 75° C. and now thecomponents (c) and (d) are added. Preferably component (d), if any, isadded first. The procedure is similar to that of step (1), wherebyelevated temperatures that may cause pre-cure are (obviously) to beavoided. The product is again sheeted off. Mixing may also be performedwith an internal mixer. For instance, using an internal mixer operatingat 64 rotations per minute, it is recommended to masticate the syntheticpolyisoprene first. To this the components (b), (f) and (c) and (d) areadded. Preferably the core temperature of the mixture is below 135° C.In step (2) the internal mixture is set to about 50° C. and firstcomponent (d) is added. Next component (c) is added. To avoid pre-cure,the core temperature of the mixture should preferably not exceed 90° C.

Preferably the mixture is allowed to maturate before use. It isrecommended for maturation to maintain the compound at about ambienttemperature for at least 2 or more hours, preferably 6 or more hours,more preferably 10 or more hours.

The composition may then be used to form the final product, bycompression moulding, extrusion moulding, injection moulding, and thelike. It is recommended for curing to use a temperature between 130 and180° C. at a curing time of 8 to 3 minutes.

Application

The composition of the present embodiments may be used in any industrialfields that can utilize its high transparency. The industrial use mayinclude, but not limited to, footwear products, tires, clothes andunderclothes, masks, rain gear, protective glasses and goggles, toys,damping materials, building components, coating material for wiring,packaging materials, protection members for computers, computerperipherals, contraceptive devices, sex toys, artificial nipple,disposable diapers, stationery, containers, food trays, balls forsports, ball chairs, and protective films.

The composition of the present embodiments may preferably be used tomanufacture footwear products such as shoe sole, tip, ornament, tongueand other parts having high transparency and strength that cannot beproduced by the conventional technique. The present composition may alsobe used to prepare a shoe which is all transparent. The footwear abovecan have both practicability and aesthetic design, and will becommercially worthwhile. A particularly preferred use concerns itsapplication as transparent shoe sole in sport shoes.

Note that the aforementioned applications are mere examples of thepresent embodiments.

EXAMPLES

Embodiments of the present disclosure will now be further illustratedwith reference to the following examples, however, without restrictingits scope to these embodiments

TABLE 1 Ingredient 1 (C) 2 3 4 5 6 (C) 7(C) 8 9(C) (a) Cariflex ® IR30747.0 46.5 46.1 45.7 45.3 75.1 — — — (a) Neodymium IR — — — — — — 47.045.7 44.8 (b) JSR RB820 47.0 46.5 46.1 45.7 45.3 — 47.0 45.7 44.8 (c)Trigonox ® 101 0.94 0.93 0.92 0.91 0.90 0.94 0.94 0.91 0.90 (d) EGDMA4.69 4.65 4.61 4.57 4.52 4.69 4.69 4.57 4.50 (e) Irganox 1726 ® 0.470.47 0.46 0.46 0.45 0.47 0.47 0.46 0.40 (f) Vestenamer ®8012 0 0.93 1.842.74 3.62 18.8 0 2.74 4.48

Example 1

Components (a), (b), and (e) were uniformly kneaded in an open roller ata temperature of ±120° C. Components (c) and (d) were added in an openroller at a temperature of ±75° C. and again the mixture was uniformlykneaded. The kneaded rubber was cut off from the roller to a sheethaving 2 mm to 3 mm thickness. The sheet was maturated at roomtemperature for one day and night.

The matured rubber was cured or vulcanized by heating press machine(manufactured by Fontijne Grotnes BV) at the temperature of 150° C. andthe pressure of 15 MPa for 6 minutes to obtain a test sample which wassubjected under the test procedures discussed hereinbefore to measurethe physical and chemical properties. The results are listed in Table 2.

Examples 2-5

Example 1 was repeated, now with addition of component (f) in the listedamounts. The results are likewise listed in Table 2.

Example 6

Example 1 was repeated, but now without component (b), and withcomponents (a) and (f) in amounts outside the present disclosure. Theresults are listed in Table 3.

Examples 7, 9 and 8

Example 1 was repeated, but now with neodymium IR as component (a), andeither without (7) or with component (f). The results are listed inTable 3.

TABLE 2 Ex. Ex. Ex. Ex. Ex. Method Property Unit 1(C) 2 3 4 5 ISO 37:Tensile MPa 9.7 10.2 10.2 8.4 10.1 2005 Strength ISO 37: Modulus MPa 3.84.3 4.2 3.8 3.9 2005 at 100% ISO 37: Elongation % 180 164 163 160 1782005 at break ASTM D624 Tear kN/m 16.8 17.9 20.9 18.7 18.3 Strength ASTMHardness 65 65.7 65.1 64.8 64.8 D2240 Shore A, 30 sec. ISO 4649,Abrasion Mm³ 140 127 76 77 61 method A ASTM Haze % 4 9.8 11.5 14.2 18.4D1003-13 ASTM Total % 91 89 86.6 84.2 80.1 D1003-13 Trans- mittance ASTME313 Yellowness 0.6 3.8 7.6 10.4 12.2 Index

TABLE 3 Ex. Ex. Ex. Ex. Method Property Unit 6(C) 7(C) 8 9(C) ISO 37:Tensile MPa 1.41 8.62 9.16 8.26 2005 Strength ISO 37: Modulus MPa 1.043.85 3.39 3.28 2005 at 100% ISO 37: Elongation % 172 151 173 169 2005 atbreak ASTM D624 Tear kN/m 6.5 21.1 18.9 20.4 Strength ASTM Hardness 40.762.4 61.7 61.2 D2240 Shore A, 30 sec. ISO 4649, Abrasion mm³ >200 212 6848 method A ASTM Haze % 92.9 23 27.4 33.2 D1003-13 ASTM Total % 63.6 8781.5 77.1 D1003-13 Trans- mittance ASTM E313 Yellowness −5.22 3.41 10.078.88 Index

1. A solid curable, transparent, rubber composition that once cured hasa haze of less than 30% and a total light transmission of more than 80%,both measured according to ASTM D1003-13, comprising: Component (a):from 35-60 wt. % of one or more synthetic isoprene polymers having arefractive index of between 1.500 to 1.525 at 23° C.; Component (b):from 35-60 wt. % of one or more transparent polymers different fromisoprene polymers wherein the difference between the refractive indicesof component (a) and (b) is 0.100 or less; Components (c) and (d): from0.05-8.0 wt. % of a curing agent, optionally with a co-agent, andComponent (e): from 0.01-20 wt. % of additives that do not influence thetransparency, characterized in that the composition further comprises:Component (f): from 1-4 wt. % of one or more polyalkenamers, wherein allamounts are in percentages by weight on the total composition.
 2. Thecomposition according to claim 1, wherein component (a) is a homopolymerof isoprene.
 3. The composition according to claim 1, wherein component(a) is a homopolymer of isoprene, made by anionic polymerization.
 4. Thecomposition according to claim 1, wherein component (a) is present in anamount of 40-55 wt. %, preferably in an amount of 45-50 wt. %.
 5. Thecomposition according to claim 1, wherein the difference between therefractive indices of component (a) and (b) is 0.050 or less, preferably0.020 or less.
 6. The composition according to claim 5, whereincomponent (b) has a mixing processing temperature of at most 150° C.,preferably at most 135° C., more preferably at most 130° C.
 7. Thecomposition according to claim 6, wherein component (b) is selected fromone or more of the group comprising butadiene polymer, polymers madefrom C₄ to C₂₀ olefins; thermoplastic elastomers (TPEs),styrene-butadiene rubber (SBR), ethylene-propylene rubber (EPM),ethylene-propylene-diene rubber (EPDM), urethane rubber.
 8. Thecomposition according to claim 1, wherein component (b) is asyndiotactic 1,2-polybutadiene rubber.
 9. The composition according toclaim 1, wherein component (b) is present in an amount of 40-55 wt. %,preferably in an amount of 45-50 wt. %.
 10. The composition according toclaim 1, wherein component (c) is a peroxide, preferably2,5-dimethyl-2,5-di-(t-butylperoxy)hexane,1,1-di(tert-butylperoxy)cyclohexane, or2,5-dimethyl-2,5-di-(t-butylperoxy)hexane.
 11. The composition accordingto claim 10, wherein a co-agent (d) is used in a weight ratio (c) to (d)of 1:2-10, preferably 1:3-7.
 12. The composition according to claim 1,wherein component (f) is a trans-polyoctenamer, preferably having atrans content of about 80%.
 13. The composition according to claim 1,having at least one of the following properties: A Type A Durometerhardness (30 sec) of 25 or more, measured according to ASTM D2240; ATear Strength of 10 N/mm or more, measured according to ASTM D624, andAn abrasion resistance of 200 mm3 or less, measured according to ISO4649, method A.
 14. A process for manufacturing a transparent, curedrubber composition from the composition according to claim 1, whereinthe process comprises the steps of: mixing components (a), (b) and (f)to obtain a mixture thereof; adding a curing agent (c) and optionally aco-agent (d); and uniformly kneading the mixture and curing the same.15. An article based on the composition according to claim
 1. 16. Thearticle according to claim 15, wherein the article is selected from thegroup consisting of footwear, tires, clothes and underclothes, raingears, eyewear, masks, toys, damping materials, building materials,coatings for wiring, packaging materials, protective members forcomputers, computer peripherals, contraceptive devices, sex toys,artificial nipples, paper diapers, stationery, containers, food trays,balls for sports, ball chairs, and protection films, seals, and keycovers.
 17. The article according to claim 16, wherein the article is atransparent sole of a shoe.
 18. An article having a composition preparedby the process according to claim 14.